Rubber composition stabilized with carnosic acid

ABSTRACT

This invention discloses a chewing gum rubber composition (gum base) that utilizes carnosic acid from a Libiatae plant, such as rosemary or sage, as an antioxidant stabilizer. This invention more specifically discloses a chewing gum base comprising: (1) about 5 weight percent to about 95 weight percent of a rubbery elastomer; (2) about 0 weight percent to about 75 weight percent of an elastomer plasticizer selected from the group consisting of natural rosin esters and synthetic terpene resins; (3) about 1 weight percent to about 65 weight percent of a filler material; and (4) carnosic acid, wherein said chewing gum base is void of sweeteners, flavoring agents or colors.

This is a continuation-in-part of U.S. patent application Ser. No.09/658,092, filed on Sep. 8, 2000, now U.S. Pat. No. 6,231,896.

BACKGROUND OF THE INVENTION

Today ordinary chewing gums and bubble gums generally utilize as theirgum base one or a combination of two or more natural or syntheticelastomers. The gum base that is selected provides the chewing gum withits masticatory properties. A chewing gum base is normally admixed withsugars or synthetic sweeteners, perfumes, flavors, plasticizers, andfillers; and then milled and formed into sticks, sheets, or pellets.Cottonseed oil is sometimes also added to give the gum softness. Styrenebutadiene rubber (SBR) is a synthetic elastomer that is widely used as agum base in chewing gums. However, SBR is not widely used inmanufacturing soft chew gums because it lacks the desired physicalproperties. Polyisobutylene is widely used in manufacturing soft chewgums even though it is much more expensive than SBR.

In any case, chewing gum compositions are typically comprised of a watersoluble bulk portion, a water insoluble chewing gum base portion andtypically water insoluble flavoring agents. The water soluble portiondissipates with a portion of the flavoring agent over a period of timeduring chewing. The gum base portion is retained in the mouth throughoutthe chewing process.

The gum base includes a number of ingredients that are subject todeterioration through oxidation during storage. The insoluble gum baseis generally comprised of elastomers, elastomer plasticizers, waxes,fats, oils, softeners, emulsifiers, fillers, texturizers andmiscellaneous ingredients, such as antioxidants, preservatives,colorants and whiteners. The compounds containing carbon—carbon doublebonds, such as fats, oils, unsaturated elastomers and elastomerplasticizers, are susceptible to oxidation. The gum base constitutesbetween 5-95% by weight of the chewing gum composition, more typically10-50% by weight of the chewing gum, and more commonly 15-35% by weightof the chewing gum.

In chewing gum base natural or artificial antioxidants are utilized tostabilize the rubbery polymer. For instance, beta-carotenes, acidulants(e.g. Vitamin C), propyl gallate, BHA, and BHT are commonly used tostabilize the rubber used in manufacturing chewing gum. Suchantioxidants are included in chewing gum base as a stabilizer to inhibitoxidation.

Antioxidants are widely used in food products susceptible todegeneration, in one form or another, due to oxidation. “Antioxidants”are defined by the Food and Drug Administration (21 CFR §170.3) as“substances used to preserve food by retarding deterioration, rancidity,or discoloration due to oxidation.” Commercial applications include usein processed meat and poultry, salad dressings, seasonings, snacks,nuts, soup bases, edible fats and oils, natural foods, pet foods andpackaging. In addition to foods, antioxidants have been used to preventoxidation in various cosmetic and toiletry products and in medicinal orpharmaceutical preparations. The primary purpose in each of theseapplications is to prevent deterioration of desirable productcharacteristics by inhibiting oxidation.

More recently, antioxidants in food sources and dietary supplements havereceived attention for their potential to prevent or delay the onset ofcertain cancers and other chronic health conditions including heartdisease, cataracts and aging. The theory is that, by preventingoxidation, these materials inhibit the formation of oxygen containingfree radicals that are believed to play a significant role in initiationof these conditions and other chronic disorders.

The use of spices to prevent food deterioration as well as to impartflavor has been known for centuries. Because of their cost andavailability, however, synthetic antioxidants, such as butylhydroxyanisole (“BHA”) and butylated hydroxytoluene (“BHT”), have beenpredominant in commercial food preparation. These antioxidants haveproven to be quite effective. However, there is currently a desire toutilize natural antioxidants in food products and chewing gum.

There is a growing desire for chewing gum base that is stabilized with anatural stabilizer. U.S. Pat. No. 4,489,099 discloses the use of VitaminE in combination with dilauryl thiodipropionate (DLTDP), as a stabilizerfor a styrene-butadiene rubber in chewing gum. U.S. Pat. No. 5,132,121,U.S. Pat. No. 5,200,213, and U.S. Pat. No. 5,270,060 disclose a use of0.01-1.00% by weight of a tocopherol mixture comprising 7-20% by weightalpha tocopherol, 45-75% by weight gamma tocopherol and 18-32% by weightdelta tocopherol to stabilize chewing gum base.

Carnosic acid is a phenolic diterpene that corresponds to the empiricalformula C₂₀H₂₈O₄. It occurs naturally in plants of the Libiatae family.For instance, carnosic acid is a constituent of the species Salviaofficinalis (sage) and Rosmarinus officinalis (rosemary) where it ismainly found in the leaves. Carnosic acid is also found in thyme andmarjoram. It was discovered by Linde in Salvia officinalis [Helv. ChimActa 47, 1234 (1962)] and by Wenkert et al. in Rosmarinus officinalis[J. Org. Chem. 30, 2931 (1965)]. It was then positively identified invarious other species of sage, such as for example Salvia canariensis[Savona and Bruno, J. Nat. Prod. 46, 594 (1983)] or Salvia willeana [dela Torre et al., Phytochemistry 29, 668 (1990)]. It is also present inSalvia triloba and Salvia sclarea.

Carnosic acid is a powerful antioxidant [Brieskorn and Domling, Z.Lebensm. Unters. Forsch. 141, 10 (1969)] and, according to a number ofRussian works where it bears the name salvine, an antibiotic againstStaphylococcus aureus [CA 86, 117603r; 90, 49011b; 97, 67513r, 69163a,69164b; 104, 221930w; 111, 130594t] and against certain microorganismsresponsible for dental caries and bad breath [CA 97, 84835q]. Inconnection with this latter property, it is disclosed in Japanese PatentPublication 59-103665 to Lion Corporation that carnosic acid can beincorporated into tooth paste and chewing gum to remove smells for themouth. Japanese Patent Publication 11180839 also discloses that carnosicacid, carnosol, and rosemanol can be used in dentifrice, mouthwash,tablets for gargling, troches, candies, and chewing gum as a deodorantfor the oral cavity.

Dried leaves of rosemary or sage contain between 1.5 and 2.5% carnosicacid and about 0.3-0.4% carnosol which is also an antioxidant. Rosmanoland rosmaridiphenol are present in smaller concentrations. Accordingly,from the point of view of the economy of a production process, carnosicacid has an indisputable advantage. According to the data disclosed inU.S. Pat. No. 4,450,097 it may be calculated that the yield of rosmanolisolated from rosemary is only 0.01%.

Wenkert et al. have demonstrated that carnosol is an oxidative artifactof carnosic acid. This oxidation takes place in the presence of oxygenboth after the harvesting of rosemary or sage in the leaves left to dryin air (it can be demonstrated that the freshly cut leaves of rosemarydo not contain carnosol) and when the leaves are subjected to extractionwith solvents or when the extracts themselves are subjected toconventional operations of fractionation, enrichment and purification.There is every reason to assume that rosmanol, which has been identifiedin a rosemary fraction subjected to an alkaline treatment, is itself asubsequent product of the oxidation of carnosic acid, as Wenkert et al.have suggested. The same may also be reasonably assumed ofrosmaridiphenol. Carnosic acid is therefore the only phenolic diterpenepresent in the native state in rosemary and sage.

Some methods for the preparation of carnosic acid by chemical synthesishave also been proposed in the literature by W. L. Meyer et al.[Tetrahedron Letters 1966, 4261; 1968, 2963; J. Org. Chem. 41, 1005(1976)]. However, the syntheses involved are long and complex and, foreconomic reasons, cannot be applied to an industrial process. Inaddition, these syntheses lead to racemic mixtures of carnosic acidprecursors and not to the pure enantiomers. It should also be pointedout that these works stop at the preparation of carnosic acid precursorsand omit to describe the final preparation step(s). Another method ofobtaining carnosic acid has been described in the literature byBrieskorn and Domling [Arch. Pharm. 302, 641 (1969)], comprising thecatalytic reduction of carnosol. Once again, the application of thisprocess on a large scale could not be envisaged on account of thenon-availability of carnosol.

U.S. Pat. No. 5,859,293 and U.S. Pat. No. 5,256,700 disclose techniquesfor extracting high purity carnosic acid from rosemary and sage. Forexample, U.S. Pat. No. 5,256,700 discloses a process for obtainingcarnosic acid comprising extracting a vegetable material selected fromthe group consisting of sage and rosemary with an apolar solvent toobtain an extract containing apolar compounds including carnosic acid,contacting the extract with an adsorbent material having an affinity forpolar compounds for adsorbing the carnosic acid to separate the carnosicacid from the apolar compounds of the extract, desorbing the adsorbentmaterial with a polar solvent to obtain the carnosic acid in the solventand then evaporating the polar solvent from the carnosic acid to obtaina residue containing the carnosic acid.

SUMMARY OF THE INVENTION

This invention is based upon the discovery that carnosic acid can beused to stabilize rubbery polymers, such as chewing gum base. Forinstance, carnosic acid can be used to protect chewing gum rubber fromoxidation and to stabilize it during processing and subsequently in thegum base and chewing gum. The carnosic acid will stabilize virtually anytype of rubbery polymer used in chewing gum, such as styrene-butadienerubber, polyisobutulene, isobutylene-isoprene copolymer elastomers,polyvinylacetate, natural gums, and mixtures thereof Some specificexamples of natural gums that can be stabilized with carnosic acidinclude jelutong, lechi caspi, perillo, massaranduba balata,massaranduba chocolate, nispero, rosindinha, chicle, gutta hang kang,and mixtures thereof.

Carnosic acid can also be used as an antioxidant in rubbers that areused in non-food applications. For example, it can be used to stabilizerubbers used in tires and industrial products, such as hoses and powertransmission belts. In fact, carnosic acid will act as an antioxidant inany unsaturated rubber (any rubber containing carbon—carbon doublebonds). Thus, carnosic acid can be used to stabilize styrene-butadienerubber, high cis-1,4-polybutadiene rubber, medium vinyl polybutadienerubber, synthesic polyisoprene rubber, natural rubber, styrene-isoprenerubber (SIR), styrene-isoprene-butadiene rubber (SIBR), nitrile rubber,carboxylated nitrile rubber, bromobutyl rubber, chlorobutyl rubber, andthe like.

The present invention more specifically discloses a chewing gum basecomprising: (1) about 5 weight percent to about 95 weight percent of arubbery elastomer; (2) about 0 weight percent to about 75 weight percentof an elastomer plasticizer selected from the group consisting ofnatural rosin esters and synthetic terpene resins; (3) about 1 weightpercent to about 65 weight percent of a filler material; and (4)carnosic acid, wherein said chewing gum base is void of sweeteners.

The subject invention also reveals a chewing gum base comprising: (1)about 5 weight percent to about 95 weight percent of a rubberyelastomer; (2) about 0 weight percent to about 75 weight percent of anelastomer plasticizer selected from the group consisting of naturalrosin esters and synthetic terpene resins; (3) about 1 weight percent toabout 65 weight percent of a filler material; and (4) carnosic acid,wherein said chewing gum base is void of flavoring agents.

The present invention further discloses a chewing gum base comprising:(1) about 5 weight percent to about 95 weight percent of a rubberyelastomer; (2) about 0 weight percent to about 75 weight percent of anelastomer plasticizer selected from the group consisting of naturalrosin esters and synthetic terpene resins; (3) about 1 weight percent toabout 65 weight percent of a filler material; and (4) carnosic acid,wherein said chewing gum base is void of colorants.

The present invention also reveals a stabilized rubber that is comprisedof a rubbery polymer and carnosic acid, wherein said stabilized rubberis void of sweeteners and/or flavoring agents. Such stabilized rubberscan also be void of colorants and humectants. The rubbery polymer can bevirtually any synthetic or natural rubber, such as styrene-butadienerubber, high cis-1,4-polybutadiene rubber, medium vinyl polybutadienerubber, natural rubber, synthetic polyisoprene rubber, styrene-isoprenerubber, styrene-isoprene-butadiene rubber, nitrile rubber, carboxylatednitrile rubber, and the like. The stabilized rubber can also be void ofthe water soluble portion that is present in chewing gum compositions.In contrast to chewing gum compositions the rubbery polymer can furthercontain carbon black and/or silica as a filler. For instance, thestabilized rubber can optionally contain from about 5 phr (parts byweight per 100 parts by weight) to about 150 phr of carbon black. Incases where carbon black is present, it will normally be employed at alevel that is within the range of about 10 phr to about 100 phr and willmore typically be present at a level that is within the range of about20 phr to about 80 phr.

DETAILED DESCRIPTION OF THE INVENTION

This invention reveals the use of carnosic acid as a stabilizer systemfor rubbery polymers. Carnosic acid is particularly useful forstabilizing chewing gum rubber compositions. The carnosic acid protectsthe rubber during processing and provides it with adequate antioxidantprotection during the service life of the final product, such as chewinggum, tires, hoses, belts, and the like. The carnosic acid used willtypically come from a plant in the Libiatae family, such as roesmary,sage, thyme or marjoram. Unfortunately, antioxidants extracted fromnaturally occuring spices generally exhibit flavors, odors, and colorsthat can be undesirable in some applications. Accordingly, efforts aretypically made to extract the carnosic acid from the plant material inhigh purity. High purity carnosic acid is typically recovered byextraction and isolation from plant matter of the Labiatae family.Various techniques for recovering carnosic acid from Labiatae plants isdisclosed in U.S. Pat. No. 5,859,293, U.S. Pat. No. 5,256,700, U.S. Pat.No. 5,061,403, and U.S. Pat. No. 4,450,097. The teachings of thesepatents are hereby incorporated herein by reference in their entirety.

It should be noted that other compounds having antioxidantcharacteristics will also frequently be present in the carnosic acidsource. For instance, carnosol, rosmanol and rosmaridiphenol will alsofrequently be present. It is believed that carnosol, rosmanol androsmaridiphenol help to further improve the stability of rubberypolymers. Thus, there is no need to make an effort to remove them fromthe carnosic acid source. In fact, the carnosol, rosmanol and/orrosmaridiphenol may act synergistically with the carnosic acid toimprove the stability of the rubbery polymer. In some applications, theflavor of the spice, such as rosemary, is desirable. In such cases it isnot necessary to highly purify the carnosic acid in an effort to removethe flavor of the spice. A rosemary extract having the aroma and flavorcharacteristics of rosemary is commercially available from Cultor FoodScience, Inc.

The chewing gum base compositions of this invention are comprised of (1)about weight percent to about 95 weight percent of a rubbery elastomer;(2) about 0 weight percent to about 75 weight percent of an elastomerplasticizer selected from the group consisting of natural rosin estersand synthetic terpene resins; (3) about 1 weight percent to about 65weight percent of a filler material; and (4) carnosic acid. The rubberyelastomer used in the chewing gum base will typically be astyrene-butadiene rubber, a polyisobutulene rubber, aisobutylene-isoprene copolymer elastomers, a polyvinylacetate, or anatural gum, such as jelutong, lechi caspi, perillo, massarandubabalata, massaranduba chocolate, nispero, rosindinha, chicle, gutta hangkang, and mixtures thereof The rubbery elastomer can, of course, also bea mixture of such natural and synthetic rubbery polymers. These chewinggum rubber compositions can then be used with excellent results as thegum base in the production of chewing gum. The chewing gum basecompositions of this invention will be employed in conjunction withother chewing gum ingredients (additives) to form chewing gum. Morespecifically, sweeteners, flavoring agents, and colorants are added tothe chewing gum base in manufacturing chewing gum. A humectant, such asaqueous sorbitol or glycerin, is also normally added to chewing gum basein manufacturing chewing gum. This is because chewing gum base,including the chewing gum base of this invention, is void of sweeteners,flavoring agents, colorants (including whiteners), and humectants.

The carnosic acid can be distributed throughout rubbery polymer using avariety of techniques known to those skilled in the art. The preferredmeans of distributing the carnosic acid throughout synthetic rubberssynthesized by emulsion polymerization is by emulsifying it with a foodgrade emulsifier and then to add it to the emulsion to the rubber. Thelatex can then be coagulated using a standard salt-acid coagulationsystem known to those skilled in the art. The rubber composition whichcontains the carnosic acid can then be processed into chewing gum orother rubber products using standard techniques. The stabilized rubbercompositions of this invention will typically contain about 0.0001 phrto about 1 phr (parts by weight per 100 parts by weight of rubber) ofcarnosic acid. The stabilized rubber compositions of this invention willmore typically contain about 0.0005 phr to about 0.1 phr of carnosicacid. The stabilized rubber compositions of this invention willpreferably contain about 0.001 phr to about 0.05 phr of carnosic acid.The stabilized rubber compositions of this invention will preferablycontain about 0.01 phr to about 0.03 phr of carnosic acid.

The emulsifier used should be suitable for emulsifying the carnosicacid. A number of food grade emulsifiers are satisfactory for thispurpose. Saponified fatty acids can be used for this purpose. Forinstance, the emulsifier can be a vegetable oil, a mono-glyceride, adiglyceride, a tri-glyceride, lecithin, a hydrogenated fat or oil, apartially hydrogenated fat or oil, an edible animal fat or oil, or asalt of a fatty acid. Salts of fatty acids, such as oleic acid, palmiticacid, steric acid, and linoleic acid are preferred. For instance, thesoap employed can be the sodium oleate, potassium oleate, sodiumpalmitate, potassium palmitate, sodium sterate, potassium sterate,sodium linoleate, potassium linoleate, or a mixture of such salts. Forexample, oleic acid (cis-9-octadecenoic acid) which has been saponifiedwith potassium hydroxide can be use as the emulsifier in the synthesisof the rubber and as the emulsifier for the carnosic acid. Oleic acidshould be protected from both air and light since on exposure to air,especially when impure, it oxidizes and acquires a yellow to brown colorand rancid odor.

After being recovered and dried the rubber containing carnosic acid canbe used in making chewing gum base. The chewing gum will incorporate therubbery polymer and, optionally, various other water-insolubleelastomeric components that contribute to the elasticity of the chewinggum and the longevity of the chew. The elastomeric component generallyconstitute about 5 to about 95 weight percent of the gum base, morepreferably about 10 to about 70 weight percent of the gum base and mostpreferably about 15 to about 45 weight percent of the gum base.

In addition to the rubbery elastomer, the gum base will typicallyinclude elastomer plasticizers, waxes, softeners/emulsifiers,fillers/texturizers, colorants, a stabilizer, and whiteners. Elastomerplasticizers constitute from about 0 to about 75 percent by weight ofthe gum base, preferably 5 to 45 percent by weight and most preferably10 to 30 percent by weight. Elastomer plasticizers include natural rosinesters such as glycerol ester of partially hydrogenated rosin, glycerolester of polymerized rosin, glycerol ester of partially dimerized rosin,glycerol ester of rosin, pentaerythritol esters of partiallyhydrogenated rosin, methyl and partially hydrogenated methyl esters ofrosin, pentaerythritol ester of rosin or mixtures thereof Elastomerplasticizers also include synthetics materials, such as terpene resinsderived from alpha-pinene, beta-pinene and/or d-limonene.

The stabilizer included in the gum base will of course contain carnosicacid. The stabilizer system will also frequently contain carnosol,rosmanol, and reomaridiphenol since they are frequently present in thecarnosic acid source. Other antioxidants such as Vitamin C, Vitamin E,and various mixtures of tocopherols, such as those described in U.S.Pat. No. 5,270,060 can also be included in the stabilizer system.

Waxes include synthetic (e.g. polyethylene and Fischer-Tropsch waxes)and natural (candelilla carnauba, beeswax, rice bran or mixturesthereof) and petroleum (e.g. microcrystalline and paraffin). Waxes, whenused, generally constitute up to 30 weight percent of the gum base.

Softeners/emulsifiers include tallow, hydrogenated tallow, hydrogenatedand partially hydrogenated vegetable oils, cocoa butter, glycerolmonostearate, glycerol triacetate, lecithin, monoglycerides,diglycerides and triglycerides, acetylated glycerides and fatty acids(e.g. stearic, palmitic, oleic, linoleic and linolenic acids) ormixtures thereof Softeners/emulsifiers generally constitute between 0.5and 40 weight percent of the gum base.

Fillers/texturizers include magnesium and calcium carbonate, groundlimestone and silicate types such as magnesium and aluminum silicate,clay, alumina, talc as well as titanium oxide, monocalcium phosphite,dicalcium phosphite and tricalcium phosphate, cellulose polymers such asethyl, methyl and wood or mixtures thereof Preferably, the fillercomprises about 1 to about 65 percent by weight of the gum base

Colorants and whiteners include FD&C-type dyes and lakes, fruit andvegetable extracts, titanium dioxide or mixtures thereof

The gum base is typically prepared by adding an amount of the elastomer,elastomer plasticizers and filler to a heated sigma blade mixer with afront to rear blade speed ratio of typically 2:1. The initial amounts ofingredients are determined by the working capacity of the mixing kettlein order to attain a proper consistency. After the initial ingredientshave massed homogeneously, the balance of the elastomer plasticizer,filler, softeners, etc. are added in a sequential manner until acompletely homogeneous molten mass is attained. This can usually beachieved in about one to about four hours, depending on the formulation.The final mass temperature can be between 60° C. and 150° C., morepreferably between 80° C. and 120° C. The completed molten mass isemptied from the mixing kettle into coated or lined pans, extruded orcast into any desirable shape and allowed to cool and solidify.

The water-soluble portion of the chewing gum may comprise softeners,sweeteners, flavoring agents and combinations thereof Softeners areadded to the chewing gum in order to optimize the chewability and mouthfeel of the gum. Softeners, also known in the art as plasticizers orplasticizing agents, generally constitute between about 0.5 to about15.0 percent by weight of the chewing gum. Softeners contemplated by thepresent invention include glycerin, lecithin, and combinations thereofFurther, aqueous sweetener solutions such as those containing sorbitol,hydrogenated starch hydrolysates, corn syrup and combinations thereofmay be used as softeners and binding agents in gum.

Bulk sweeteners constitute between 20-80% by weight of the chewing gumand may include both sugar and sugarless sweeteners and components.Sugar sweeteners may include saccharide-containing components includingbut not limited to sucrose, maltose, dextrin, dried invert sugar,levulose, galactose, corn syrup solids, and the like, alone or incombination. The sugar can also be a monosaccharides of 5 or 6 carbonatoms, such as arabinose, xylose, ribose, glucose, mannose, galactose,fructose, dextrose, or sorbose or mixtures of two or more of theforegoing monosaccharides, disaccharides, for example, sucrose such ascane or beet sugar, lactose, maltose or cellobiose; polysaccharides,such as partially hydrolyzed starch or dextrin.

Sugarless sweeteners include components with sweetening characteristicsbut are devoid of the commonly known sugars. Sugarless sweetenersinclude, but are not limited to, sugar alcohols such as sorbitol,mannitol, xylitol, hydrogenated starch hydrolysates, maltitol, and thelike, alone or in combination. Some additional examples of artificialsweeteners which may be employed include sodium, calcium or ammoniumsaccharin salts, free saccharin and, dihydrochalcones, dipotassiumglycyrrhizin, glycyrrhizic acid ammonium salt,L-aspartyl-L-phenylalanine methyl ester (aspartame), the sodium orpotassium salt of3,4-dihydro-6-methyl-1,2,3-oxathiazine-4-one-2,2-dioxide(Ace-sulfame-K), as well as Stevia rebaudiana (Stevioside), Richardelladulcifica (Miracle Berry), Diascoreophyllum cumminsii (SerendipityBerry), cyclamate salts, and the like, or mixtures of any two or more ofthe above.

High intensity sweeteners can also be present. Such high intensitysweeteners may include but are not limited to sucralose, aspartame,salts of acesulfame, alitame, saccharin and its salts, cyclamic acid andits salts, dihydrochalcones, thaumatin, monellin, and the like, alone orin combination.

Combinations of sugar and/or sugarless sweeteners may be used in thechewing gum. The sweetener may also function in the chewing gum in wholeor in part as a water soluble bulking agent. Additionally, the softenermay also provide additional sweetness, such as with aqueous sugar oralditol solutions.

One or more flavoring agents may be present in the chewing gum in anamount within the range of about 0.1 to about 10.0 percent andpreferably from about 0.5 to about 5.0 weight percent of the gum. Theflavoring agents may comprise essential oils, natural or syntheticflavors or mixtures thereof including but not limited to oils derivedfrom plants and fruits such as citrus oils, fruit essences, peppermintoil, spearmint oil, other mint oils, clove oil, oil of wintergreen,anise, and the like. Artificial flavoring agents and components are alsocontemplated. Those skilled in the art will recognize that natural andartificial flavoring agents may be combined in various acceptablefashions. Optional ingredients such as emulsifiers and pharmaceuticalagents may also be added to the chewing gum. For instance, from about0.05 weight percent to about 3 weight percent of a fluoridatingingredient can be added to the chewing gum for the prevention of dentalcaries. Some representative examples of fluoridating agents that can beused include alkali metal fluorides, ammonium fluoride, stannousfluoride, stannous chlorofluoride, potassium stannous fluoride, alkalimetal monofluorophosphates, ammonium monofluorophosphate, and the like.

In general, chewing gum is manufactured by sequentially adding thevarious chewing gum ingredients to a commercially available mixer knownin the art. After the ingredients have been thoroughly mixed, the gummass is discharged from the mixer and shaped into the desired form suchas by rolling into sheets and cutting into sticks, extruding intochunks, or casting into pellets.

Generally, the ingredients are mixed by first softening (e.g. with heat)the gum base and adding it to the running mixer. The gum base can alsobe softened in the mixer itself Color or emulsifiers may also be addedat this time. A softener, such as glycerin, may also be added at thistime along with syrup and a portion of the bulking agent. Furtherportions of the bulking agent portion may then be added to the mixer. Aflavoring agent is typically added with the final portion of the bulkingagent.

The entire mixing procedure typically takes from five to fifteenminutes, but longer mixing times may sometimes be required. Thoseskilled in the art will recognize that variations of the above describedprocedure, or different procedures, may be followed.

This invention is illustrated by the following example that are merelyfor the purpose of illustration and are not to be regarded as limitingthe scope of the invention or the manner in which it can be practiced.Unless specifically indicated otherwise, parts and percentages are givenby weight.

EXAMPLE

In this experiment SBR latex was stabilized by adding 0.3 phr ofGuardian GP (from Cultor Food Science) thereto. Guardian GP is a naturalextract of rosemary containing carnosic acid having the aroma and flavorcharacteristics of rosemary. The SBR latex was subsequently coagulatedand dried.

The stabilized SBR was then aged at 70° C. in a forced air circulatingoven for 28 days. The elastic modulus (G′) at 50 rpm and Mooney ML1+4viscosity at 100° C. of the SBR sample were measured after 3 days, 7days, 14 days, 21 days, and 28 days. A control SBR that was stabilizedwith 0.3 phr of BHA was also evaluated. The results of this evaluationare shown in Table I (Mooney ML 1+4 viscosity) and Table II (G′).

TABLE I Mooney ML1+4 Viscosity at 100° Days of Aging Carnosic AcidStabilized BHA Stabilized  0 55.7 54.7  3 60.2 55.7  7 60.3 50 14 58.432.8 21 58.4 30.8 28 55 33.6

TABLE II G′ at 50 rpm Days of Aging Carnosic Acid Stabilized BHAStabilized  0 80.3 81.9  3 80.3 78.0  7 79.6 68.9 14 77.3 46.7 21 77.327.6 28 75.7 25.2

This experiment shows that the carnosic acid in the rosemary extract washighly effective at maintaining original elastic properties after heataging for 28 days. In fact, the carnosic acid proved to be superior forstabilizing the SBR as compared to BHA.

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

What is claimed is:
 1. A stabilized rubber composition comprising arubbery elastomer and a sufficient amount of carnosic acid to stabilizethe rubber composition, wherein said stabilized rubber composition isvoid of a water soluble portion.
 2. A stabilized rubber composition asspecified in claim 1 wherein said stabilized rubber composition is voidof sweeteners.
 3. A stabilized rubber composition as specified in claim1 wherein said stabilized rubber composition is void of flavoringagents.
 4. A stabilized rubber composition as specified in claim 1wherein said stabilized rubber composition is void of colorants.
 5. Astabilized rubber composition as specified in claim 1 wherein thecarnosic acid is present at a level which is within the range of about0.0001 phr to about 1 phr.
 6. A stabilized rubber composition asspecified in claim 5 wherein said stabilized rubber composition isfurther comprised of an additional antioxidant selected from the groupconsisting of carnosol, rosmanol and rosmaridiphenol.
 7. A stabilizedrubber composition as specified in claim 1 wherein the carnosic acid ispresent at a level which is within the range of about 0.0005 phr toabout 0.1 phr.
 8. A stabilized rubber composition as specified in claim1 wherein the carnosic acid is present at a level which is within therange of about 0.001 phr to about 0.05 phr.
 9. A stabilized rubbercomposition as specified in claim 1 wherein the carnosic acid is presentat a level which is within the range of about 0.01 phr to about 0.03phr.
 10. A stabilized rubber composition as specified in claim 1 whereinsaid stabilized rubber composition is void of humectants.
 11. Astabilized rubber composition comprising: (1) a rubbery elastomer, (2)carbon black, and (3) a sufficient amount of carnosic acid to stabilizethe rubber composition.
 12. A stabilized rubber composition as specifiedin claim 11 wherein the carnosic acid is present at a level which iswithin the range of about 0.0001 phr to about 1 phr.
 13. A stabilizedrubber composition as specified in claim 12 wherein the carbon black ispresent at a level which is within the range of about 10 phr to about100 phr.
 14. A stabilized rubber composition as specified in claim 12wherein the carbon black is present at a level which is within the rangeof about 20 phr to about 80 phr.
 15. A stabilized rubber composition asspecified in claim 11 wherein the carnosic acid is present at a levelwhich is within the range of about 0.0005 phr to about 0.1 phr.
 16. Astabilized rubber composition as specified in claim 11 wherein thecarnosic acid is present at a level which is within the range of about0.001 phr to about 0.05 phr.
 17. A stabilized rubber composition asspecified in claim 11 wherein the carnosic acid is present at a levelwhich is within the range of about 0.01 phr to about 0.03 phr.
 18. Astabilized rubber composition as specified in claim 11 wherein thecarbon black is present at a level which is within the range of about 5phr to about 150 phr.
 19. A stabilized rubber composition comprising:(1) a rubbery elastomer, (2) silica, and (3) a sufficient amount ofcarnosic acid to stabilize the rubber composition.